In existing Code Division Multiple Access (CDMA) systems utilizing closed loop transmit diversity, base stations having multiple antennas use an antenna weight coefficient factor to adjust the phase and/or relative amplitude of signals transmitted from each antenna. In such systems, a mobile station computes a set of optimized antenna coefficients that should be applied at the base station antennas to maximize the mobile received signal power. The mobile station then feeds back to the base station a set of antenna control bits for use by the base station in generating the optimized antenna weights. While receiving high speed downlink packet access channels, the mobile station also feeds back a Channel Quality Indication (CQI) for use by the base station in transmissions scheduling and Transport Format (TF) selection, namely, the transmission power, transport block size, modulation scheme, number of channels to be sent in a time slot. In prior art closed loop transmit diversity systems, the channel quality information is computationally complex and includes a number of inherent inaccuracies.
It would be desirable to provide a method of determining channel quality information in a high speed downlink packet access communication system with closed loop transmit diversity that reduces the need for hardware and/or software resources within a mobile station forming part of the communication system. It would moreover be advantageous to provide a method for determining channel quality information that is improved upon the accuracy of existing methods. It would also be desirable to provide a method of determining channel quality information in a high speed downlink packet access communication system with closed loop transmit diversity that ameliorates or overcomes one or more problems associated with existing channel quality information determining methods, or at least provides a practical alternative thereto.